Epoxy body (DO-41) · Ø 2.7 × 5.2 mm1N5819 · Vƒ ≈ 0.45 VCathode band (gray)Pins (anode / cathode)

Black DO-41 body, gray cathode stripe, “1N5819” text
DO-41 body ≈ 5 × 2.7 mm

Diodes

Schottky diode

In simple terms

What is this?

A fast one-way gate that loses very little energy; it holds you up only slightly as you pass.

What is it for?

Very little voltage drops across it; energy is not wasted in battery and switching circuits.

Where do you see it?

Phone chargers, solar panels and battery-powered devices.

How do you spot it?

A black cylinder that looks like a normal diode, with a stripe at one end; you tell it apart by the code on top.

Caution:

It has low tolerance of reverse voltage and leaks a little in the reverse direction; check its label.

Technical definition

A diode made from a metal–semiconductor junction instead of a P-N junction. Its forward voltage drop is small and it switches very fast. The price is that reverse leakage current is higher than a normal diode’s and its reverse voltage limit is low.

Forward voltage≤ 0.6 V (1 A)

Reverse voltage40 V

Current1 A

Schematic symbol Same in IEC and ANSI

IEC 60617: the drawing style used in Türkiye and Europe.

Pins 2

1Anode (A)Unstriped sideA

2Cathode (K)Striped sideK

Features typical

Max. reverse voltage: 40 V
Average current: 1 A
Forward voltage: ≤ 0.6 V (1 A)
Surge current: 25 A
Reverse leakage: ≤ 1 mA (25 °C, 40 V)
Streak: 1N5817: 20 V · 1N5818: 30 V · 1N5819: 40 V
Example part: 1N5819 (40 V, 1 A)

Common mistakes

Exceeding the reverse voltage1N5819 withstands only 40 V. Use 1N4007 for higher-voltage rectification.

Ignoring leakage currentReverse leakage grows as it warms. In battery-powered circuits that sit idle for long periods, this leakage can slowly drain the battery.

Test with a multimeter

Test whether this part is good with the multimeter on the measurement screen.

Take a measurement

Where it is used

Low-loss reverse battery protectionSwitching regulator diodeBlocking reverse current in a solar panelChoosing the supply from two sources

Try it in the Lab